1. Field of Invention
The present invention relates to a method for diagnosing and controlling an unusual hydraulic state of hybrid vehicle transmission. More particularly, the present invention relates to a method for diagnosing and controlling an unusual hydraulic state of hybrid vehicle transmission which may determine the unusual hydraulic state of hybrid vehicle transmission when a contamination problem occurs in the transmission and eliminate foreign substances quickly.
2. Description of Related Art
A vehicle having a hybrid transmission which is composed of an engine, a motor-generator, and a planetary gear generally drives by an electric vehicle mode in starting and low speed section. After that, when the vehicle gains speed, the vehicle drives in a power distribution mode in which uses the power of the engine and the motor-generator more effectively by applying electrically variable transmission (EVT). Further the vehicle may use a fixed gear ratio for improving power performance of the vehicle. A system based on the above mentioned concepts has been developed for improving power performance, fuel-efficiency of vehicle, idle stop, and regeneration braking.
However, a shifting shock and an unusual shifting phenomenon can be happened when a hydraulic problem occurs in the transmission of hybrid vehicle just like a transmission of gasoline vehicle. There was no special method for diagnosis and countermeasure when these problems happen since the hydraulic pressure is impossible to measure in a real time.
The conventional art was trying to solve the problem by testing the performance of hydraulic pressure of transmission assembly, reproducing the problem, disassembling the transmission assembly, and analyzing. Therefore, the conventional art may bring serious danger to the user since the conventional art cannot quickly diagnose and solve the hydraulic problem of the hybrid vehicle transmission.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.